Thanks, Rocketnia. I had actually placed each pair on its own line with a carriage return, but the text editor kept removing it upon posting.
I came up with this list keeping Arc/Nu as the proposed name for the pure Arc implementation, and then was left with the '/Nu' slice as the only way to keep the product association. So that left only the Arc component to play with. My personal preference is ax/nu: a -> Arc and x -> extended. Ax/Nu also has the benefit of brevity, IMHO.